Changes in the lungs have been found to be associated with flare ups of chronic obstructive pulmonary disease (COPD), according to a study.

Scientists used computer tomography (CT) to identify two types of structural alterations in the lungs of COPD patients which are linked to a worsening of symptoms, according to a paper published in journal Radiology.

One of the main structural abnormalities observed were emphysema, during which the air sacs of the lung are progressively destroyed.

The second issue was airway disease, which triggers a narrowing of bronchial tubes.

COPD is usually assessed using a spirometer, which measures the volume of air in the lungs and how fast it is breathed out.

However, lead researcher MeiLan K Han argued that this device is "inadequate" for assessing the risk of COPD exacerbations.

"Two COPD patients may be identical in terms of lung function yet behave very differently. For instance, there are subsets of patients with severely reduced lung function who do not experience frequent exacerbations," he explained.

Health Secretary Andrew Lansley recently announced a new strategy to tackle the UK's high mortality rate for asthma and COPD.